What Is a Colonoscopy and Why Is It Performed?
A colonoscopy is a medical test that allows a doctor to look inside your large intestine (colon and rectum) using a long, flexible tube called a colonoscope. This tube has a tiny camera and light at the tip, so the doctor can see the lining of your colon on a monitor. The test helps find abnormal growths (like polyps), inflammation, bleeding, or signs of cancer.
Colonoscopy is considered the best way to check for colorectal problems early because the doctor can not only see but also remove small growths or take small tissue samples (biopsies) during the same procedure. It is often recommended for routine screening or when you have symptoms like abdominal pain, bleeding, or changes in bowel habits.
Purpose & Benefits of Colonoscopy
● Detects precancerous polyps so they can be removed before turning into cancer.
● Finds colorectal cancer at an early stage, when treatment is most effective.
● Diagnoses causes of symptoms such as bleeding, cramping, or unexplained weight loss.
● Enables biopsy (tissue sampling) for accurate diagnosis.
● Helps manage chronic conditions like ulcerative colitis or Crohn’s disease.
● Can reduce the need for later surgery by catching problems early.
Who May Need a Colonoscopy?
A colonoscopy may be recommended when:
● Routine colorectal cancer screening is due (commonly beginning at age 45 or earlier with risk factors).
● You have rectal bleeding, persistent abdominal pain, or chronic changes in bowel habits.
● There is a family history of colon cancer or polyps.
● You have unexplained iron-deficiency anaemia or chronic fatigue linked to blood loss.
● Prior tests (like stool blood tests) are abnormal and need further evaluation.
● Follow-up after previous polyps or colorectal disease to monitor changes.
Your doctor considers your age, symptoms, and medical history before deciding when to schedule a colonoscopy.
Types of Colonoscopies
Screening Colonoscopy
Used to check for cancer and polyps in people with no symptoms, usually starting at a recommended age.
Diagnostic Colonoscopy
Done when you have symptoms or abnormal tests, such as bleeding, pain, or a positive stool test.
Surveillance Colonoscopy
For people with a history of polyps, cancer, or inflammatory bowel disease, regular follow-up exams are done to watch for new problems.
Colonoscopy Procedure: Step-by-Step
1. Before your appointment, you will follow a clear-liquid diet and take special solutions or laxatives the day before to clean out your colon completely. This is very important so the doctor can see the colon lining clearly.
2. At the clinic or hospital, your nurse reviews your health history and explains the steps. You will be asked to change into a gown.
3. Most people receive sedation or light anaesthesia so they remain comfortable and relaxed during the procedure.
4. The doctor gently inserts the lubricated colonoscope through the rectum and slowly advances it through the colon.
5. The camera sends images to a screen so the doctor can inspect the entire colon lining for any abnormalities.
6. If polyps or suspicious areas are found, the doctor may remove them or take small samples (biopsies) through the scope.
7. The colonoscope is slowly withdrawn, and the procedure usually takes about 20–40 minutes.
Afterward, you are taken to a recovery area while the effects of sedation wear off.
Recovery & Aftercare
● You may feel fullness, mild cramping, or gas; this usually goes away quickly.
● Because of sedation, you will need a responsible adult to drive you home.
● Avoid strenuous activity and alcohol for the rest of the day.
● You can typically eat and drink normally after the procedure unless advised otherwise.
● If polyps were removed, your doctor may give specific instructions about diet, activity, and when to resume medications.
Most people feel back to normal within a day.
Risks & Possible Complications
Colonoscopy is very safe, but like any medical procedure, it has potential risks:
● Bleeding, especially if a polyp was removed.
● Perforation (small tear) in the colon wall, rare but serious.
● Reaction to sedation or anaesthesia.
● Infection
● Abdominal discomfort or bloating after the test.
Your care team will discuss these risks before the procedure and answer any questions.
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